6
$\begingroup$

Why doesn't the earth have a ring?

If solid material such as dust and moonlets, and common components of satellite systems are brought nearer to the Earth, then what will happen? Will it take the form of a ring or fall down on the Earth?

$\endgroup$
6
$\begingroup$

Most planets don't have rings. The ring region is inside the Roche limit which is quite close to the planet. A ring system outside the Roche limit needs to be either very faint or, it would over time coalesce into a moon or possibly pair of moons at Trojan points to each other.

There's different Roche limits for rocky bodies vs icy, but an icy body couldn't exist in Earth's orbit for long, so it's not really relevant for the Earth. Saturn's rings are mostly ice, which extends about twice as far as the rocky body Roche limit.

enter image description here

How long a ring system lasts depends on a few factors. How big it is, whether it's given new material regularly or not, what it's made of and how vulnerable it is to the sun's rays. Saturn's rings, for example, are losing material, raining down on Saturn as well as slowly adding material from Enceladus, one of it's small and close moon's that gives up ring material by tidal-volcanic eruptions.

Earth's large moon could (not saying it would but it might) play a role in disrupting and Earth-Ring system more quickly than it would with no moon. A 2 body system with the 2nd body as large as the moon isn't gravitationally friendly to other orbiting objects.

Many man made satellites orbit well within the Roche limit but they are small enough to be held together and not be affected by tidal forces. Larger objects, just a few miles across, perhaps less, are more vulnerable to tidal forces and tend to break up inside the Roche Limit.

| improve this answer | |
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.